Punching unit for punching apparatus

A punching unit for punching apparatus comprising a punch removably mounted on an upper half side of a support section formed in a substantial channel shape such that said punch will face a die mounted on a lower half side of said support section;

• and a lifting mechanism movably mounted on said support section, for vertically moving said punch, and removably connected to said punch, said punching unit further comprising:
• a flat force-cutting blade attached at a bottom end of said punch, and a rotating mechanism provided in said support section for rotatably mounting said punch on said support section and for turning said punch through 90 degrees so that the sides of a square hole may be successively punched, wherein a mounting cylinder having an inserting bore is fixedly mounted in said upper half of said support section;
• said punch loaded with a spring acting upwardly, is rotatably and vertically movably inserted in said inserting bore of said mounting cylinder;
• and said punch and said lifting mechanism are mounted by a connector fixedly installed at a top end of said punch, wherein said rotating mechanism comprises a fluid cylinder, a shaft for rotatably supporting said cylinder in the upper half of said support section, an arm secured to said connector, a shaft connecting said cylinder to said arm, and two stoppers for limiting the range of movement of said arm and setting the angle of rotation of said punch to 90 degrees.